Snail (Helix aspersa) exposure history and possible adaptation to lead as reflected in shell composition

Abstract

Lead sequestration in shell was examined for English and Welsh populations of the common garden snail (Helix aspersa) with different Pb exposure histories. Isotopic Pb ratios provided signatures for Pb source and a means of implying duration of population exposure from decades to millennia. Total Pb concentrations were used to quantify the intensity of exposure experienced by the populations. Snails from populations with long histories of exposure (millennia) to high Pb levels had proportionately more Pb in their shell than soft tissue compared with snails from other surveyed populations. These observations suggest that Pb sequestration in shell has been enhanced in H. aspersa populations with long and intense exposure to Pb.